Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
hanh trang » thanh trung, canh tranh, hanh trinh
kien sach » dien sach, vien bach, kien mac
trang cap » trung cap, trong cap, tranh chap
cap nhung » cam nhung, vap nhung, dap nhung
hoc kien » hoc hien, hoc vien, hoa kien

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc kien sach - hanh trang cap nhung cong ((tan tran) OR (((bai toan) OR (bai tap)))) cau~.
• Adding a wildcard symbol may retrieve word variants: hoc kien sach - hanh trang cap nhung cong ((tan tran) or (((bai toan) or (bai tap)))) cau*.